delete LinAlg/SystemOfLinearEquations dir and make LinAlg/Lis dir
add LisCheck.h
add LisVector
add LisMatrix
add LisTools
add LisLinearSolver
change LisLinearSolver constructor as it takes LisMatrix and option as arguments
remove unnecessary log output
add is_assembled variable in LisMatrix because lis_matrix_is_assembled() is not working.
Changes to cleanup class LisMatrix.

- Reformatted code
- Made docu more meaningful
- Changed name of first parameter of constructor
- Moved implementation of setValue() and getValue() from header into cpp-file
Some code cleanup in LisLinearSolver.